CMP is a combination of chemical reaction and mechanical buffing. A conventional CMP system includes a polishing head with a retaining ring that holds and rotates a substrate (also referred to interchangeably as a wafer) against a polishing pad surface rotating in the same direction. The polishing pad can be made of cast and sliced polyurethane (or other polymers) with a filler or a urethane coated felt.
During rotation of the substrate against the polishing pad, a slurry of silica (and/or other abrasives) suspended in a mild etchant, such as potassium or ammonium hydroxide, is dispensed onto the polishing pad. The combination of chemical reaction from the slurry and mechanical buffing from the polishing pad removes vertical inconsistencies on the surface of the substrate, thereby forming an extremely flat surface.
After a pad is used, it must be removed from a platen on which it rests, which can be labor intensive and time consuming and can result in injury to an operator. The effort needed and the potential for injury is due to the high force required to overcome the attachment of the pad to the platen caused by a pressure sensitive adhesive disposed between the pad and platen. Further, the effort and potential for injury has increased as the industry has moved from 200 mm wafers to 300 mm wafer since the larger surface area of pads used increases the force required to remove them from platens.
Therefore, a new polishing pad removal apparatus and method are needed that overcome the above-mentioned shortcomings while substantially decreasing the amount of human effort required.